Construction costs are currently skyrocketing

Quite simple. It is also called an apples-to-oranges comparison.

So you want to compare an apartment that is in a residential block located on the Havel in Potsdam, and the residential block then contains about 15 housing units, with a house that would stand there alone even though you cannot get any plots there?

Find the mistake :)

That is called an apple-to-Tesla comparison :-)

No, he accuses you of comparing apples and oranges, if you compared an apartment in possibly a better location with a house JWD. I can confirm for myself that this is also the case for me (the other side of Berlin) with 1:1 comparable properties in terms of construction/purchase (for new rentals). At least until now. It could be that the Berlin real estate market collapses in the next 10 years and rents also decrease - but I don't believe that.

It may be that the Berlin real estate market collapses in the next 10 years and rents also decrease

No way. Especially not Berlin. They will just implement their rent control again, which will result in even less housing being available. So everything will just keep getting more expensive.

No, he accuses you of comparing apples and oranges, like comparing an apartment in possibly a better location with a house in the middle of nowhere. I can confirm for myself that, on my side of Berlin, it also tends towards construction/purchase even with 1:1 comparable properties (in new rentals). At least so far. It could be that the Berlin real estate market collapses in the next 10 years and rents also go down - but I don't believe that.

I understand. But how am I supposed to compare a house in the same location if there are no plots of land in that location?

Well, the comparison is flawed, so you would have to compare an apartment building of similar size and features, in the same location as the property. That is more likely.

I understand. But how am I supposed to compare a house in the same location if there are no plots of land in that location?

That is exactly what I want to get at. If there were plots there, they would certainly be well outside the price range. So I buy/build in a less desirable, probably worse location. Then the whole calculation regarding what is cheaper (purely economically) does not work out. With the €1500 cold rent, I will very likely get a significantly better location than with my house construction. Maybe that even saves a car? Or or... Calculating renting versus buying is already difficult due to many variables. If you then add different locations, it probably becomes impossible to do the calculation.